Author(s)

R. L. Frederick & F. Acuña

Abstract

Two dimensional transient modelling of the flow and heat transfer in an idealized Trombe wall system was performed for a fixed set of physical dimensions. The governing equations were solved using multiphysics software. Buoyancy and thermal accumulation in a brick wall are the main effects considered. During operation, the solid and fluid temperatures constantly increase, while circulation flow rates, which are significant from the start, show a slow decrease. The room is heated by the parallel mechanisms of buoyancy flow from the collector space and directly by the hot wall, but the latter effect becomes progressively more important. Heat losses through the glazed surfaces of room and collector are of similar magnitude. However, when the wall clearances are closed the collector loss shows an important increase. The role of the typical Trombe wall circulation in the control of heat losses is discussed. Keywords: Trombe wall system, natural convection, numerical models. 1 Introduction In this paper a two dimensional simulation of a conventional Trombe wall system is described. The importance of passive solar heating systems in latitudes that favour winter solar collection on vertical walls has increased in recent years. These systems are known to depend on buoyancy as the main driving force for air flow, and on the accumulation of energy by a massive wall for thermal comfort in periods of time without solar energy input [1, 2]. Given the low flow rates that occur in such devices, the Trombe wall system is a very interesting subject for numerical simulation, especially because the experimentation in such systems is still relatively expensive. The thermal performance of Trombe wall systems has been studied by experimental and numerical methods. Numerical predictions of the thermal

Keywords

Trombe wall system, natural convection, numerical models.